Lens barrel

ABSTRACT

A lens barrel includes a radially-retractable optical element constituting a part of photographing optical system, and is movable between a photographing position and a radially-retracted position; a biasing device for biasing the radially-retractable optical element toward the photographing position; and a swing member which is rotatable about a rotation axis extending parallel to the optical axis, the swing member being rotated so as to push the radially-retractable optical element against a biasing force of the biasing device to move the radially-retractable optical element to the radially-retracted position. The radially-retractable optical element and the swing member are mutually positioned so that a moving amount of the radially-retractable optical element per unit of rotation angle of the swing member gradually decreases as the radially-retractable optical element moves from the photographing position to the radially-retracted position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a lens barrel, and particularly, to alens barrel having a radially-retractable optical element which iscapable of radially retracting away from a photographing optical axisposition to a radially-retracted position.

2. Description of the Related Art

Generally, in a telescoping lens barrel in which a photographing opticalaxis is not deflected by use of a mirror or a prism, the length of thelens barrel in the retracted (accommodated) state thereof cannot be madeshorter than the total thickness of the optical elements of thephotographing optical system in the optical axis direction thereof.Nevertheless, there has been a demand for a further reduction in lengthof the retracted photographic lens to achieve an extra-shortphotographic lens. As a solution to this demand, the assignee of theprevent invention has proposed a zoom lens whose length, in a retractedstate, is further reduced by radially retracting a part of thephotographing optical system away from the photographing optical axisthereof. This zoom lens is disclosed in United States Patent PublicationNo. US2003/0156832 A1.

SUMMARY OF THE INVENTION

The present invention provides a lens barrel in which the load on aretracting driving device such as a motor is reduced by reducing thevariation of the resistance for the radially retracting operation of theradially-retractable optical element.

According to an aspect of the present invention, a lens barrel isprovided, including a radially-retractable optical element constitutinga part of photographing optical system, the radially-retractable opticalelement being movable between a photographing position located on anoptical axis of the photographing optical system, and aradially-retracted position located on an off-optical-axis position; abiasing device for biasing the radially-retractable optical elementtoward the photographing position; and a swing member which is rotatableabout a rotation axis extending parallel to the optical axis, the swingmember being rotated so as to push the radially-retractable opticalelement against a biasing force of the biasing device to move theradially-retractable optical element to the radially-retracted position.The radially-retractable optical element and the swing member aremutually positioned so that a moving amount of the radially-retractableoptical element per unit of rotation angle of the swing member graduallydecreases as the radially-retractable optical element moves from thephotographing position to the radially-retracted position.

It is desirable for the biasing force of the biasing device to varyaccording to the movement of the radially-retractable optical elementand becomes maximum when the radially-retractable optical element ispositioned at the radially-retracted position.

It is desirable for the lens barrel to include a linear guiding device,wherein the radially-retractable optical element is linearly guided bythe linear guiding device so as to move between the photographingposition and the radially-retracted position in a direction orthogonalto the optical axis.

It is desirable for the linearly guiding device of theradially-retractable optical element to include a guide shaft extendingparallel to a retracting direction of the radially-retractable opticalelement; and an optical-element holder which holds theradially-retractable optical element, the optical-element holderslidably supported by the guide shaft so as to move between thephotographing position and the radially-retracted position of theradially-retractable optical element. The swing member rotationallymoves while pushing the optical-element holder against the biasing forceof the biasing device when the radially-retractable optical element ismoved from the photographing position to the radially-retractedposition.

It is desirable for the rotation axis of the swing member to bepositioned so that a force applying portion, at which the swing memberpushes the optical-element holder, gradually approaches the guidingshaft as the radially-retractable optical element moves from thephotographing position to the radially-retracted position.

It is desirable for the swing member to include a rotatable lever, oneend thereof being rotatably supported by the pivot, and the other endthereof being provided with the force applying portion.

It is desirable for the lens barrel to include a rotational biasingmember for rotationally biasing the swing member in a direction so as tohold the radially-retractable optical element in the photographingposition.

It is desirable for the lens barrel to include a rotational ring whichis driven to rotate about a rotational axis parallel to the optical axisby a motor so as to cause at least one optical element, which isdifferent from the radially-retractable optical element, to move alongthe optical axis; and a rotation transmitting device for transmitting arotational driving force of the rotational ring to the swing member whenthe radially-retractable optical element moves from the photographingposition to the radially-retracted position.

It is desirable for the radially-retractable optical element to includean image sensor provided in an imaging position of the photographingoptical system.

It is desirable for the lens barrel to include an image-stabilizer whichdetects vibration applied to the photographing optical system and movesthe radially-retractable optical element in a plane orthogonal to theoptical axis, when the radially-retractable optical element is in thephotographing position, to counteract image shake in accordance with adirection and a magnitude of the vibration.

In an embodiment, a lens barrel is provided, including aradially-retractable optical element constituting a part of aphotographing optical system, the radially-retractable optical elementbeing movable between a photographing position located on an opticalaxis of the photographing optical system, and a radially-retractedposition located on an off-optical-axis position; a biasing device forbiasing the radially-retractable optical element toward thephotographing position; and a swing member which is rotatable about arotation axis extending parallel to the optical axis, the swing memberbeing rotated so as to push the radially-retractable optical elementagainst a biasing force of the biasing device to move theradially-retractable optical element to the radially-retracted position.A biasing force of the biasing device gradually increases, and a movingamount of the radially-retractable optical element per unit rotationangle of the swing member gradually decreases, as theradially-retractable optical element moves from the photographingposition to the radially-retracted position.

According to the present invention described above, the variation of theresistance for the radially retracting operation of theradially-retractable optical element can be reduced to thereby reducethe load on the retracting driving device.

The present disclosure relates to subject matter contained in JapanesePatent Application No. 2004-349189 (filed on Dec. 1, 2004), which isexpressly incorporated herein by reference in its entirety.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described below in detail with referenceto the accompanying drawings in which:

FIG. 1 is a cross-sectional view of an embodiment of a retractable zoomlens to which the present invention is applied in the retracted state ofthe zoom lens barrel;

FIG. 2 is a cross-sectional view of the zoom lens shown in FIG. 1 in aphotographic state of the zoom lens;

FIG. 3 is an enlarged cross-sectional view of a part of the zoom lens atthe wide-angle extremity thereof;

FIG. 4 is an enlarged cross-sectional view of a part of the zoom lens atthe telephoto extremity thereof;

FIG. 5 is a block diagram illustrating a configuration of electricalcircuits of a camera equipped with the zoom lens shown in FIGS. 1 and 2;

FIG. 6 is a conceptual diagram showing the moving paths of a helicoidring and a cam ring and the moving paths of a first lens group and asecond lens group by movement of the cam ring;

FIG. 7 is a conceptual diagram showing the combined moving path of eachof the first lens group and the second lens group, in which the movingpaths of the helicoid ring and the cam ring are included;

FIG. 8 is an exploded perspective view of the zoom lens shown in FIGS. 1and 2;

FIG. 9 is an exploded perspective view of elements of an imagestabilizing mechanism and a radially-retracting mechanism which areshown in FIG. 8;

FIG. 10 is a front perspective view of the image stabilizing mechanismand the radially-retracting mechanism, illustrating the retracted stateof a CCD holder in the retracted state of the zoom lens shown in FIG. 1;

FIG. 11 is a front perspective view of the image stabilizing mechanismand the radially-retracting mechanism, illustrating the optical-axisadvanced state of the CCD holder in a photographic state of the zoomlens;

FIG. 12 is a rear perspective view of a portion of the image stabilizingmechanism as viewed from the rear side of FIGS. 10 and 11;

FIG. 13 is a front elevational view of the image stabilizing mechanismand the radially-retracting mechanism in the state shown in FIG. 10, asviewed from the front in the optical axis direction;

FIG. 14 is a front elevational view of the image stabilizing mechanismand the radially-retracting mechanism in the state shown in FIG. 11, asviewed from the front in the optical axis direction;

FIG. 15 is a rear perspective view of the zoom lens in the retractedstate of the zoom lens shown in FIG. 1;

FIG. 16 is a front perspective view of a horizontal moving frame and avertical moving frame which support the CCD holder, and associatedelements;

FIG. 17 is a front view of the horizontal moving frame, the verticalmoving frame and the associated elements shown in FIG. 16;

FIG. 18 is a rear view of the horizontal moving frame, the verticalmoving frame and the associated elements shown in FIGS. 16 and 17;

FIG. 19 is a cross-sectional view of the CCD holder, the horizontalmoving frame, the vertical moving frame and other elements, taken alongD1-D1 line shown in FIG. 17;

FIG. 20 is a front elevational view of the elements shown in FIGS. 16through 17 and other associated elements, illustrating an imagestabilizing action in the horizontal direction by an operation of ahorizontal driving lever;

FIG. 21 is a front elevational view of the elements shown in FIG. 20,illustrating an image stabilizing action in the vertical direction by anoperation of a vertical driving lever;

FIG. 22 is a front elevational view of elements of the image stabilizingmechanism and the radially-retracting mechanism, illustrating theretracted state of the CCD holder, the horizontal moving frame and thevertical moving frame which are retracted by an operation of aretracting lever;

FIG. 23 is a front elevational view of the elements shown in FIG. 22,illustrating a state in which the CCD holder, the horizontal movingframe and the vertical moving frame return to their respectivephotographing positions where the CCD holder is positioned on thephotographing optical axis when the retracting lever is disengaged fromthe vertical moving frame to stop upholding the vertical moving frame;and

FIG. 24 is a front elevational view of elements shown in FIG. 8 forillustrating the relationship between the horizontal driving lever andthe vertical motion of the CCD holder, the horizontal moving frame, andthe vertical moving frame.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show cross-sections of a zoom lens 10 which isincorporated in a zoom lens camera. The zoom lens 10 is provided with abox-shaped housing 11 and a retractable barrel portion 12 retractablysupported inside the housing 11. The outside of the housing 11 iscovered by exterior components of the camera; the exterior componentsare not shown in the drawings. A photographing optical system of thezoom lens 10 includes a first lens group 13 a, a shutter 13 b, adiaphragm 13 c, a second lens group 13 d, a third lens group(radially-retractable optical element) 13 e, a low-pass filter(radially-retractable optical element) 13 f, and a CCD image sensor(radially-retractable optical element) 13 g (hereinafter referred to asCCD), in that order from the object side (the left side as viewed inFIGS. 1 and 2). As shown in FIG. 5, the CCD 13 g is electricallyconnected to a control circuit 14 a having an image processing circuit.Thus, an electronic image can be displayed on an LCD monitor 14 bprovided on an outer surface of the camera, and the electronic imagedata can be recorded in a memory 14 c. In a photographic state(ready-to-photograph state) of the zoom lens 10 shown in FIG. 2, all ofthe optical elements constituting the photographing optical system arealigned on the same photographing optical axis Z1. On the other hand, inan accommodated (radially retracted) state of the zoom lens 10 shown inFIG. 1, the third lens group 13 e, the low-pass filter 13 f and the CCD13 g are moved away from the photographing optical axis Z1 to beradially retracted upward in the housing 11, and the second lens group13 d is linearly retracted into the space created as a result of theupward radial retracting movement of the third lens group 13 e, thelow-pass filter 13 f and the CCD 13 g, which reduces the length of thezoom lens 10 in the retracted state thereof. The overall structure ofthe zoom lens 10 that includes a radially-retracting mechanism forradially retracting optical elements upward will be describedhereinafter. In the following description, the vertical direction andthe horizontal direction of the zoom lens camera body equipped with thezoom lens 10 as viewed from the front thereof are defined as a y-axisand an x-axis, respectively.

The housing 11 is provided with a hollow box-shaped portion 15 and ahollow fixed ring portion 16 which is formed on a front wall 15 a of thebox-shaped portion 15 so as to enclose the photographing optical systemabout the photographing optical axis Z1. A rotation center axis Z0serving as the center of the fixed ring portion 16 is parallel to thephotographing optical axis Z1 and eccentrically located below thephotographing optical axis Z1. A retraction space (accommodation space)SP (FIGS. 1 and 2) is formed inside the box-shaped portion 15 and abovethe fixed ring portion 16.

A zoom gear 17 (FIGS. 8, 10 and 11) is supported on an inner peripheralsurface side of the fixed ring portion 16 to be rotatable on an axis ofrotation parallel to the rotation center axis Z0. The zoom gear 17 isrotated forward and reverse by a zoom motor MZ (FIGS. 5, 10, and 11)supported by the housing 11. In addition, the fixed ring portion 16 isprovided on an inner peripheral surface thereof with a female helicoid16 a, a circumferential groove 16 b and a plurality of linear guidegrooves 16 c (only one of them is shown in FIG. 8). The circumferentialgroove 16 b is an annular groove with its center on the rotation centeraxis Z0, while the plurality of the linear guide grooves 16 c areparallel to the rotation center axis Z0 (see FIGS. 3, 4 and 8).

A helicoid ring (rotational ring) 18 is supported inside the fixed ringportion 16 to be rotatable about the rotation center axis Z0. Thehelicoid ring 18 is provided with a male helicoid 18 a which is engagedwith the female helicoid 16 a of the fixed ring portion 16 and thus canadvance and retract in the optical axis direction while rotating due tothe engagement of the female helicoid 16 a with the male helicoid 18 a.The helicoid ring 18 is further provided, on an outer peripheral surfacethereof in front of the female helicoid 18 a, with a plurality ofrotation guiding protrusions 18 b (only two of them are shown in FIG.8). In a state shown in FIGS. 2 through 4 in which the helicoid ring 18advances to the frontmost position thereof with respect to the fixedring portion 16, the female helicoid 16 a and the male helicoid 18 a aredisengaged from each other while the plurality of rotation guidingprotrusions 18 b are slidably fitted in the circumferential groove 16 bso that the helicoid ring 18 is prevented from further moving in theoptical axis direction and is allowed only to rotate at a fixed positionin the optical axis direction. The helicoid ring 18 is further providedon threads of the male helicoid 18 a with an annular spur gear 18 cwhich is in mesh with the zoom gear 17. Teeth of the spur gear 18 c arealigned parallel to the photographing optical axis Z1. The zoom gear 17is elongated in the axial direction thereof so as to remain engaged withthe spur gear 18 c at all times over the entire range of movement of thehelicoid ring 18 from a retracted state of the helicoid ring 18 shown inFIGS. 1 and 10 to an extended state of the helicoid ring 18 shown inFIGS. 2 and 11. The helicoid ring 18 is constructed by combining tworing members which are splittable in the optical axis direction. InFIGS. 10 and 11, only the rear ring member of the helicoid ring 18 isshown.

A linear guide ring 20 is supported inside the helicoid ring 18. Thelinear guide ring 20 is provided in the vicinity of the rear end thereofwith a linear guide projection 20 a, and is guided linearly along therotation center axis Z0 (and the photographing optical axis Z1) by theslidable engagement of the linear guide projection 20 a with the linearguide groove 16 c of the fixed ring portion 16 as shown in FIG. 4. Arotation guiding portion 21 is provided between the inner peripheralsurface of the helicoid ring 18 and the outer peripheral surface of thelinear guide ring 20. The helicoid ring 18 is supported by the linearguide ring 20 to be rotatable with respect to the linear guide ring 20and to be movable together with the linear guide ring 20 in the opticalaxis direction via the rotation guiding portion 21. The rotation guidingportion 21 consists of a plurality of circumferential grooves providedat different positions in the axial direction and radial protrusions,each of which is slidably engaged in the corresponding circumferentialgroove (see FIGS. 3 and 4).

The linear guide ring 20 is provided on an inner peripheral surfacethereof with a plurality of linear guide grooves 20 b (only one of themis shown in each of FIGS. 1 through 4) which extend parallel to therotation center axis Z0 (and the photographing optical axis Z1). Aplurality of linear guide projections 22 a (only one of them is shown ineach of FIGS. 1 through 4) which project radially outwards from a firstlens group linear guide ring 22 and a plurality of linear guideprojections 23 a (only one of them is shown in each of FIGS. 1 through4) which project radially outwards from a second lens group linear guidering 23 are slidably engaged with the plurality of linear guide grooves20 b, respectively. The first lens group linear guide ring 22 guides afirst lens group support frame 24 linearly in a direction parallel tothe rotation center axis Z0 (and the photographing optical axis Z1) viaa plurality of linear guide grooves 22 b (only one of them is shown ineach of FIGS. 2 and 3) formed on an inner peripheral surface of thefirst lens group linear guide ring 22. The second lens group linearguide ring 23 guides a second lens group support frame 25 linearly in adirection parallel to the rotation center axis Z0 (and the photographingoptical axis Z1) via a plurality of linear guide keys 23 b (only one ofthem is shown in each of FIGS. 1 through 4). The first lens groupsupport frame 24 supports the first lens group 13 a via a focusing frame29, and the second lens group support frame 25 supports the second lensgroup 13 d.

A cam ring 26 is provided inside the linear guide ring 20 to berotatable about the rotation center axis Z0. The cam ring 26 issupported by the first lens group linear guide ring 22 and the secondlens group linear guide ring 23 to be rotatable with respect to each ofthe first lens group linear guide ring 22 and the second lens grouplinear guide ring 23 and to movable in the optical axis directiontogether therewith via rotation guiding portions 27 and 28 (see FIG. 4).As shown in FIGS. 3 and 4, the rotation guiding portion 27 is composedof a discontinuous circumferential groove 27 a (not shown in FIG. 3)which is formed on an outer peripheral surface of the cam ring 26, andan inner flange 27 b which projects radially inwards from the first lensgroup linear guide ring 22 to be slidably engaged in the discontinuouscircumferential groove 27 a. As shown in FIGS. 3 and 4, the rotationguiding portion 28 is composed of a discontinuous circumferential groove28 a (not shown in FIG. 3) formed on an inner peripheral surface of thecam ring 26 and an outer flange 28 b which projects radially outwardsfrom the second lens group linear guide ring 23 to be slidably engagedin the discontinuous circumferential groove 28 a.

As shown in FIG. 4, the cam ring 26 is provided thereon with a pluralityof follower protrusions 26 a (only one of them is shown in FIG. 4) whichproject radially outwards. The plurality of follower protrusions 26 apasses through a plurality of follower guide slots 20 c (only one ofthem is shown in FIG. 4) formed in the linear guide ring 20 to beengaged in a plurality of rotation transfer grooves 18 d (only one ofthem is shown in FIG. 4) formed on an inner peripheral surface of thehelicoid ring 18. Each rotation transfer groove 18 d is parallel to therotation center axis Z0 (and the photographing optical axis Z1), andeach follower protrusion 26 a is slidably engaged in the associatedrotation transfer groove 18 d to be prevented from moving in thecircumferential direction relative to the associated rotation transfergroove 18 d. Accordingly, the rotation of the helicoid ring 18 istransferred to the cam ring 26 via the engagement between the pluralityof rotation transfer grooves 18 d and the plurality of followerprotrusions 26 a. Although the development shape of each follower guidegroove 20 c is not shown in the drawings, each follower guide groove 20c is a guide groove including a circumferential groove portion with itscenter on the rotation center axis Z0 and an inclined lead grooveportion parallel to the female helicoid 16 a. Accordingly, when rotatedby a rotation of the helicoid ring 18, the cam ring 26 rotates whilemoving forward or rearward along the rotation center axis Z0 (and thephotographing optical axis Z1) if each follower protrusion 26 a isengaged in the lead groove portion of the associated follower guidegroove 20 c, and rotates at a fixed position in the optical axisdirection without moving forward or rearward if each follower protrusion26 a is engaged in the circumferential groove portion of the associatedfollower guide groove 20 c.

The cam ring 26 is a double-sided cam ring having a plurality of outercam grooves 26 b (only one of them is shown in FIG. 3) and a pluralityof inner cam grooves 26 c (only one of them is shown in each of FIGS. 3and 4) on outer and inner peripheral surfaces of the cam ring 26,respectively. The plurality of outer cam grooves 26 b are slidablyengaged with a plurality of cam followers 24 a (only one of them isshown in FIG. 3) which project radially inwards from the first lensgroup support frame 24, respectively, while the plurality of inner camgrooves 26 c are slidably engaged with a plurality of cam followers 25 a(only one of them is shown in each of FIGS. 3 and 4) which projectradially outwards from the second lens group support frame 25.Accordingly, when the cam ring 26 is rotated, the first lens groupsupport frame 24 that is guided linearly in the optical axis directionby the first lens group linear guide ring 22 moves forward and rearwardalong the rotation center axis Z0 (and the photographing optical axisZ1) in predetermined motion in accordance with contours of the pluralityof outer cam grooves 26 b likewise, when the cam ring 26 is rotated, thesecond lens group support frame 25 that is guided linearly in theoptical axis direction by the second lens group linear guide ring 23moves forward and rearward along the rotation center axis Z0 (and thephotographing optical axis Z1) in predetermined motion in accordancewith contours of the plurality of the plurality of inner cam grooves 26c.

The second lens group support frame 25 is provided with a cylindricalportion 25 b (see FIGS. 1 and 2) which holds the second lens group 13 d,and supports the shutter 13 b and the diaphragm 13 c in front of thecylindrical portion 25 b to allow each of the shutter 13 b and thediaphragm 13 c to be opened and closed. The shutter 13 b and thediaphragm 13 c can be opened and closed by a shutter actuator MS and adiaphragm actuator MA, respectively, which are supported by the secondlens group support frame 25 (see FIGS. 5 and 15).

The focusing frame 29 which holds the first lens group 13 a is supportedby the first lens group support frame 24 to be movable along therotation center axis Z0 (and the photographing optical axis Z1). Thefocusing frame 29 can be moved forward and rearward by a focusing motorMF (see FIG. 5).

The operation of each of the zoom motor MZ, the shutter actuator MS, thediaphragm actuator MA and the focusing motor MF is controlled by thecontrol circuit 14 a. Upon turning on a main switch 14 d (see FIG. 5) ofthe camera, the zoom motor MZ is driven to bring the zoom lens 10 to thephotographic state shown in FIG. 2. Upon turning off the main switch 14d, the zoom lens 10 is moved from the photographic state to theretracted state shown in FIG. 1.

The above described operation of the zoom lens 10 is summarized asfollows. Upon turning on the main switch 14 d in the retracted state ofthe zoom lens 10 shown in FIG. 1, the zoom gear 17 is driven to rotatein a lens barrel advancing direction. Accordingly, the helicoid ring 18moves forward in the optical axis direction while rotating, andsimultaneously, the linear guide ring 20 linearly moves forward in theoptical axis direction together with the helicoid ring 18. In addition,the rotation of the helicoid ring 18 causes the cam ring 26 to moveforward in the optical axis direction while rotating relative to thelinear guide ring 20. The first lens group linear guide ring 22 and thesecond lens group linear guide ring 23 linearly move forward in theoptical axis direction together with the cam ring 26. Each of the firstlens group support frame 24 and the second lens group support frame 25moves in the optical axis direction relative to the cam ring 26 inpredetermined motion. Therefore, the moving amount of the first lensgroup 13 a in the optical axis direction when the zoom lens 10 isextended from the retracted state thereof is determined by adding themoving amount of the cam ring 26 relative to the fixed ring portion 16to the moving amount of the first lens group support frame 24 relativeto the cam ring 26 (the advancing/retracting amount of the first lensgroup support frame 24 by the cam groove 26 b). Furthermore, the movingamount of the second lens group 13 d in the optical axis direction whenthe zoom lens 10 is extended from the retracted state thereof isdetermined by adding the moving amount of the cam ring 26 relative tothe fixed ring portion 16 to the moving amount of the second lens groupsupport frame 25 relative to the cam ring 26 (the advancing/retractingamount of the second lens group support frame 25 by the cam groove 26c).

FIG. 6 shows the moving paths of the helicoid ring 18 and the cam ring26 and the moving paths of the first lens group 13 a and the second lensgroup 13 d relative to the cam ring 26 (the cam diagrams of the camgrooves 26 b and 26 c). The vertical axis represents the amount ofrotation (angular position) of the lens barrel from the retracted stateof the zoom lens 10 to the telephoto extremity thereof, and thehorizontal axis represents the amount of movement of the lens barrel inthe optical axis direction. As shown in FIG. 6, the helicoid ring 18 ismoved forward in the optical axis direction while rotating up to anangular position θ1 which is located at about the midpoint in the rangeof extension of the zoom lens 10 from the retracted position (shown inFIG. 1) to the wide-angle extremity (shown by the upper half of the zoomlens 10 from the photographing optical axis Z1 and shown in FIG. 2),whereas the helicoid ring 18 rotates at a fixed position in the opticalaxis direction as described above in the range of extension of the zoomlens 10 from the angular position θ1 to the telephoto extremity (shownby the lower half of the zoom lens 10 from the photographing opticalaxis Z1 and shown in FIG. 4). On the other hand, the cam ring 26 ismoved forward in the optical axis direction while rotating up to anangular position θ2 which is located immediately behind the wide-angleextremity of the zoom lens 10 in the range of extension of the zoom lens10 from the retracted position to the wide-angle extremity, whereas thecam ring 26 rotates at a fixed position in the optical axis direction asdescribed above in the range of extension of the zoom lens 10 from theangular position θ2 to the telephoto extremity, similar to the helicoidring 18. In the zooming range from the wide-angle extremity to thetelephoto-extremity, the moving amount of the first lens group 13 a inthe optical axis direction is determined from the moving amount of thefirst lens group support frame 24 relative to the cam ring 26 whichrotates at a fixed position in the optical axis direction (theadvancing/retracting amount of the first lens group support frame 24 viathe cam groove 26 b), while the moving amount of the second lens group13 d in the optical axis direction is determined from the moving amountof the second lens group support frame 25 relative to the cam ring 26which rotates at a fixed position in the optical axis direction (theadvancing/retracting amount of the second lens group support frame 25via the cam groove 26 c). The focal length of the zoom lens 10 is variedby the relative movement in the optical axis direction between the firstlens group 13 a and the second lens group 13 d. FIG. 7 shows the actualmoving path of the first lens group 13 a which is obtained by combiningthe moving amounts of the helicoid ring 18 and the cam ring 26 with themoving amount of the first lens group 13 a by the cam groove 26 b, andthe actual moving path of the second lens group 13 d which is obtainedby combining the moving amounts of the helicoid ring 18 and the cam ring26 with the moving amount by the cam groove 26 c.

In the zooming range from the wide-angle extremity to the telephotoextremity, a focusing operation is performed by moving the first lensgroup 13 a in the optical axis direction independently of other opticalelements by the focusing motor MF.

The operations of the first lens group 13 a and the second lens group 13d have been described above. In the zoom lens 10 of the presentembodiment, the optical elements of the zoom lens 10 from the third lensgroup 13 e to the CCD 13 g are retractable away from the photographingposition on the photographing optical axis Z1 to an off-optical-axisretracted position (radially retracted position) Z2 located above thephotographing position as described above. In addition, by moving theoptical elements from the third lens group 13 e to the CCD 13 g on aplane perpendicular to the photographing optical axis Z1, image shakecan also be counteracted. The retracting mechanism and the imagestabilizing mechanism will be discussed hereinafter.

As shown in FIGS. 8 and 19, the third lens group 13 e, the low-passfilter 13 f and the CCD 13 g are held by a CCD holder 30 to be providedas a unit. The CCD holder 30 is provided with a holder body 30 a, asealing member 30 b and a pressure plate 30 c. The third lens group 13 eis held by the holder body 30 a at a front end aperture thereof. Thelow-pass filter 13 f is held between a flange formed on an inner surfaceof the holder body 30 a and the sealing member 30 b, and the CCD 13 g isheld between the sealing member 30 b and the pressure plate 30 c. Theholder body 30 a and the pressure plate 30 c are fixed to each other bythree fixing screws 30 d (see FIGS. 15 and 18) separately arrangedaround the central axis of the CCD holder 30 (the photographing opticalaxis Z1 in a photographic state of the zoom lens 10). The three fixingscrews 30 d also secure one end portion of an image transmissionflexible PWB 31 to the rear surface of the pressure plate 30 c so that asupporting substrate of the CCD 13 g is electrically connected to theimage transmission flexible PWB 31.

The image transmission flexible PWB 31 extends from its connection endat the CCD 13 g to the retraction space SP in the housing 11. The imagetransmission flexible PWB 31 is provided with a first linear portion 31a, a U-shaped portion 31 b, a second linear portion 31 c, and a thirdlinear portion 31 d (see FIGS. 1 and 2). The first linear portion 31 ais substantially orthogonal to the photographing optical axis Z1 andextends upward. The U-shaped portion 31 b is bent forward from the firstlinear portion 31 a. The second linear portion 31 c extends downwardfrom the U-shaped portion 31 b. The third linear portion 31 d is foldedupward from the second linear portion 31 c. The third linear portion 31d is fixed to an inner surface of the front wall 15 a of the housing 11therealong. The first linear portion 31 a, the U-shaped portion 31 b andthe second linear portion 31 c (except the third linear portion 31 d)serve as a free-deformable portion which is freely resilientlydeformable according to the motion of the CCD holder 30.

The CCD holder 30 is supported by a horizontal moving frame 32 via threeadjusting screws 33 (see FIGS. 15 and 18) separately arranged around thecentral axis of the CCD holder 30 (the photographing optical axis Z1 ina ready-photograph state of the zoom lens 10). Three compression coilsprings 34 are installed between the CCD holder 30 and the horizontalmoving frame 32. The shaft portions of the three adjusting screws 33 areinserted into the three compression coil springs 34, respectively. Whenthe tightening amounts of the adjusting screws 33 are changed, therespective compression amounts of the coil springs 34 are changed. Theadjusting screws 33 and the compression coil springs 34 are provided atthree different positions around the optical axis of the third lensgroup 13 e, and accordingly, the inclination of the CCD holder 30 withrespect to the horizontal moving frame 32, or the inclination of theoptical axis of the third lens group 13 e with respect to thephotographing optical axis Z1, can be adjusted by changing thetightening amounts of the three adjusting screws 33.

As shown in FIG. 16, the horizontal moving frame 32 is supported by avertical moving frame (linear guiding device) 36 to be movable withrespect thereto via a horizontal guide shaft 35 extending in the x-axisdirection. Specifically, the horizontal moving frame 32 is provided witha rectangular frame portion 32 a which encloses the CCD holder 30 and anarm portion 32 b which extends horizontally from the frame portion 32 a.A spring supporting protrusion 32 c is formed on an upper surface of theframe portion 32 a, and an inclined surface 32 d and a positionrestricting surface 32 e are formed on an end portion of the arm portion32 b. The position restricting surface 32 e is a flat surface parallelto the y-axis. On the other hand, the vertical moving frame 36 isprovided with a pair of motion restricting frames 36 a and 36 b, aspring supporting portion 36 c, an upper bearing portion 36 d, and alower bearing portion 36 e. The pair of motion restricting frames 36 aand 36 b are provided spaced apart in the x-axis direction. The springsupporting portion 36 c is located between the pair of the motionrestricting frames 36 a and 36 b. The upper bearing portion 36 d islocated on a line extended from the spring supporting portion 36 c inthe x-axis direction. The lower bearing portion 36 e is located belowthe upper bearing portion 36 d. As shown in FIG. 17, the horizontalmoving frame 32 is supported by the vertical moving frame 36 in a statewhere the frame portion 32 a is positioned in the space between the pairof motion restricting frames 36 a and 36 b and where the inclinedsurface 32 d and the position restricting surface 32 e of the armportion 32 b are positioned between the motion restricting frame 36 band the upper bearing portion 36 d.

One end of the horizontal guide shaft 35 is fixed to the motionrestricting frame 36 a of the vertical moving frame 36, and the otherend of the horizontal guide shaft 35 is fixed to the upper bearingportion 36 d of the vertical moving frame 36. Two through-holes arerespectively formed in the motion restricting frame 36 b and the springsupporting portion 36 c to be horizontally aligned to each other so asto allow the horizontal guide shaft 35 to pass through the motionrestricting frame 36 b and the spring supporting portion 36 c.Horizontal through-holes 32 x 1 and 32 x 2 (see FIG. 17) into which thehorizontal guide shaft 35 is inserted are formed in the arm portion 32 band the spring supporting protrusion 32 c of the horizontal moving frame32, respectively. The horizontal through-holes 32 x 1 and 32 x 2 of thehorizontal moving frame 32 and the aforementioned two through-holeswhich are respectively formed in the motion restricting frame 36 b andthe spring supporting portion 36 c are horizontally aligned with eachother. Since the horizontal guide shaft 35 is slidably fitted in thehorizontal through-holes 32 x 1 and 32 x 2, the horizontal moving frame32 is supported by the vertical moving frame 36 to be movable withrespect to the vertical moving frame 36 in the x-axis direction. Ahorizontal moving frame biasing spring 37 is installed on the horizontalguide shaft 35 between the spring supporting protrusion 32 c and thespring supporting portion 36 c. The horizontal moving frame biasingspring 37 is a compression coil spring and biases the horizontal movingframe 32 in a direction (leftward as viewed in FIG. 17) to make thespring supporting protrusion 32 c approach the motion restricting frame36 a.

Vertical through-holes 36 y 1 and 36 y 2 (see FIG. 16) are furtherformed in the upper bearing portion 36 d and the lower bearing portion36 e of the vertical moving frame 36, respectively, which extend in aline along the y-axis direction which is orthogonal to the photographingoptical axis Z1. The vertical through-hole 36 y 1 and the verticalthrough-hole 36 y 2 are vertically aligned, and a vertical guide shaft(linear guiding device) 38 (see FIGS. 8 and 9) passes through verticalthrough-hole 36 y 1 and the vertical through-hole 36 y 2. Both ends ofthe vertical guide shaft 38 are fixed to the housing 11, and therefore,the vertical moving frame 36 can move along the vertical guide shaft 38in the y-axis direction inside the camera. More specifically, thevertical moving frame 36 can move between the photographing positionshown in FIG. 1 and the retracted position shown in FIG. 2. When thevertical moving frame 36 is positioned in the photographing position asshown in FIG. 2, the centers of the third lens group 13 e, the low-passfilter 13 f and the CCD 13 g in the CCD holder 30 are positioned on thephotographing optical axis Z1. When the vertical moving frame 36 ispositioned in the radially retracted position as shown in FIG. 1, thecenters of the third lens group 13 e, the low-pass filter 13 f and theCCD 13 g are positioned in the off-optical-axis retracted position Z2that is located above the fixed ring portion 16.

The vertical moving frame 36 is provided with a spring hooking portion36 f which projects horizontally from a side surface of the verticalmoving frame 36 in a direction away from the vertical through-hole 36 y1, and a vertical moving frame biasing spring (biasing device) 39 isextended between the spring hooking portion 36 f and a spring hookingportion 11 a (see FIGS. 8 and 15) fixed to the housing 11 therein. Thevertical moving frame biasing spring 39 is an extension coil spring andbiases the vertical moving frame 36 downward (i.e., toward thephotographing position thereof shown in FIG. 2).

As described above, the horizontal moving frame 32 that holds the CCDholder 30 is supported by the vertical moving frame 36 to be movable inthe x-axis direction with respect to the vertical moving frame 36, andthe vertical moving frame 36 is supported by the housing 11 via thevertical guide shaft 38 to be movable in the y-axis direction withrespect to the housing 11. Image shake can be counteracted by moving theCCD holder 30 in the x-axis direction and the y-axis direction. To thisend, a horizontal driving lever 40 and a vertical driving lever 41 areprovided as elements of a driving mechanism which achieves such movementof the CCD holder 30. The horizontal driving lever 40 and the verticaldriving lever 41 are pivoted on a lever pivot shaft 42 to be rotatable(swingable) independently of each other. The lever pivot shaft 42 ispositioned in the housing 11 and fixed thereto to be parallel to thephotographing optical axis Z1.

As shown in FIGS. 9 and 20, the horizontal driving lever 40 is pivotedat the lower end thereof on the lever pivot shaft 42, and is provided atthe upper end of the horizontal driving lever 40 with a force-applyingend 40 a. The horizontal driving lever 40 is provided in the vicinity ofthe force-applying end 40 a with an operation pin 40 b which projectsrearward in the optical axis direction and a spring hooking portion 40 cwhich projects forward in the optical axis direction. As shown in FIG.12, the force-applying end 40 a of the horizontal driving lever 40 abutsagainst a lug 43 b of a first moving member 43. The first moving member43 is supported by a pair of parallel guide bars 44 (44 a and 44 b) tobe slidable thereon in the x-axis direction, and a driven nut member 45abuts against the first moving member 43. The driven nut member 45 isprovided with a female screw hole 45 b and a rotation restricting groove45 a (see FIG. 9) which is slidably fitted on the guide bar 44 b. Adrive shaft (a feed screw) 46 a of a first stepping motor 46 is screwedinto the female screw hole 45 b. As shown in FIGS. 13 and 14, the drivennut member 45 abuts against the first moving member 43 from the leftside. One end of an extension coil spring 47 is hooked on the springhooking portion 40 c of the horizontal driving lever 40, and the otherend of the spring 47 is hooked on a spring hooking portion 11 b whichprojects from an inner surface of the housing 11 (see FIG. 12). Theextension coil spring 47 biases the horizontal driving lever 40 in adirection to bring the first moving member 43 to abut against the drivennut member 45, i.e., in a counterclockwise direction as viewed in FIGS.13, 14 and 20. Due to this structure, driving the first stepping motor46 causes the driven nut member 45 to move along the pair of guide bars44, and at the same time causes the first moving member 43 to movetogether with the driven nut member 45, thus causing the horizontaldriving lever 40 to swing about the lever pivot shaft 42. Specifically,moving the driven nut member 45 rightward as viewed in FIGS. 13 and 14causes the driven nut member 45 to press the first moving member 43 inthe same direction against the biasing force of the extension spring 47,thus causing the horizontal driving lever 40 to rotate clockwise asviewed in FIGS. 13 and 14. Conversely, moving the driven nut member 45leftward as viewed in FIGS. 13 and 14 causes the first moving member 43to move in the same direction while following the leftward movement ofthe driven nut member 45 due to the biasing force of the extension coilspring 47, thus causing the horizontal driving lever 40 to rotatecounterclockwise as viewed in FIGS. 13 and 14.

As shown in FIG. 20, the operation pin 40 b of the horizontal drivinglever 40 abuts against the position restricting surface 32 e that isprovided on the end portion of the arm portion 32 b of the horizontalmoving frame 32. Since the horizontal moving frame 32 is biased leftwardas viewed in FIG. 20 by the horizontal moving frame biasing spring 37,the operation pin 40 b remains in contact with the position restrictingsurface 32 e. When the horizontal driving lever 40 swings, the positionof the operation pin 40 b changes along the x-axis direction, so thatthe horizontal moving frame 32 moves along the horizontal guide shaft35. Specifically, rotating the horizontal driving lever 40 clockwise asviewed in FIG. 20 causes the operation pin 40 b to press the positionrestricting surface 32 e, which causes the horizontal moving frame 32 tomove rightward as viewed in FIG. 20 against the biasing force of thehorizontal moving frame biasing spring 37. Conversely, rotating thehorizontal driving lever 40 counterclockwise as viewed in FIG. 20 causesthe operation pin 40 b to move in a direction away from the positionrestricting surface 32 e (leftward as viewed in FIG. 20), which causesthe horizontal moving frame 32 to move in the same direction whilefollowing the leftward movement of the operation pin 40 b due to thebiasing force of the horizontal moving frame biasing spring 37.

As shown in FIGS. 9 and 21, the vertical driving lever 41 is pivoted atits lower end on the lever pivot shaft 42, as in the case of thehorizontal driving lever 40, and is provided at the upper end of thevertical driving lever 41 with a force-applying end 41 a. The verticaldriving lever 41 is longer than the horizontal driving lever 40, and theforce-applying end 41 a protrudes upward to a position higher than theposition of the force-applying end 40 a. The vertical driving lever 41is provided between the lever rotating shaft 42 and the force-applyingend 41 a with a pressing inclined surface 41 b which projects rightwardas viewed in FIG. 21. The vertical driving lever 41 is provided abovethe pressing inclined surface 41 b with a spring hooking portion 41 c.As shown in FIG. 12, the force-applying end 41 a abuts against a lug 50b of a second moving member 50. The second moving member 50 is supportedby a pair of parallel guide bars 51 (51 a and 51 b) to be slidablethereon in the x-axis direction, and a driven nut member 52 abutsagainst the second moving member 50. The driven nut member 52 isprovided with a female screw hole 52 b and a rotation restricting groove52 a which is slidably fitted on the guide bar 51 b. A drive shaft (afeed screw) 53 a of a second stepping motor 53 is screwed into thefemale screw hole 52 b. As shown in FIGS. 13 and 14, the driven nutmember 52 abuts against the second moving member 50 from the left sideas viewed from the front of the camera. One end of an extension coilspring 54 is hooked on the spring hooking portion 41 c of the verticaldriving lever 41, and the other end of the spring 54 is hooked on aspring hooking portion (not shown) formed on an inner surface of thehousing 11. The extension coil spring 54 biases the vertical drivinglever 41 in a direction to bring the second moving member 50 to abutagainst the driven nut member 52, i.e., in the counterclockwisedirection as viewed in FIGS. 13, 14, and 21. Due to this structure,driving the second stepping motor 53 causes the driven nut member 52 tomove along the pair of guide bars 51, and at the same time causes thesecond moving member 50 to move together with the driven nut member 52,thus causing the vertical driving lever 41 to swing about the leverpivot shaft 42. Specifically, moving the driven nut member 52 rightwardas viewed in FIGS. 13 and 14 causes the driven nut member 52 to pressthe second moving member 50 in the same direction against the biasingforce of the extension spring 54, thus causing the vertical drivinglever 41 to rotate clockwise as viewed in FIGS. 13 and 14. Conversely,moving the driven nut member 52 leftward as viewed in FIGS. 13 and 14causes the second moving member 50 to move in the same direction whilefollowing the leftward movement of the driven nut member 52 due to thebiasing force of the extension spring 54, thus causing the verticaldriving lever 41 to rotate counterclockwise as viewed in FIGS. 13 and14.

As shown in FIG. 21, the pressing inclined surface 41 b of the verticaldriving lever 41 can come into contact with a pressed pin 36 g whichprojects forward from the upper bearing portion 36 d of the verticalmoving frame 36. Since the vertical moving frame 36 is biased downwardsas viewed in FIG. 21 by the vertical moving frame biasing spring 39, thepressed pin 36 g always remains in contact with the pressing inclinedsurface 41 b. When the vertical driving lever 41 swings, the abuttingangle of the pressing inclined surface 41 b relative to the pressed pin36 g changes, so that the vertical moving frame 36 moves along thevertical guide shaft 38. Specifically, rotating the vertical drivinglever 41 clockwise as viewed in FIG. 21 causes the pressing inclinedsurface 41 b to press the pressed pin 36 g upward as viewed in FIG. 21,which causes the vertical moving frame 36 to move upward against thebiasing force of the vertical moving frame biasing spring 39.Conversely, rotating the vertical driving lever 41 counterclockwise asviewed in FIG. 21 causes the abutting point on the pressing inclinedsurface 41 b relative to the pressed pin 36 g to descend, which causesthe vertical moving frame 36 to move downward by the biasing force ofthe vertical moving frame biasing spring 39.

In the above-described structure, the horizontal moving frame 32 can becaused to move left or right in the x-axis direction by driving thefirst stepping motor 46 forward or reverse. Furthermore, the verticalmoving frame 36 can be caused to move upwards or downwards in the y-axisdirection by driving the second stepping motor 53 forward or reverse.

The first moving member 43 is provided with a plate portion 43 a, andthe second moving member 50 is provided with a plate portion 50 a. Theinitial position of the horizontal moving frame 32 can be detected by aphoto sensor 55 having a light emitter and a light receiver which arespaced apart from each other as shown in FIGS. 8, 10 and 11 when theplate portion 43 a passes between the light emitter and the lightreceiver of the photo sensor 55. The plate portion 43 a and the photosensor 55 constitute a photo interrupter. Likewise, the initial positionof vertical moving frame 36 can be detected by a photo sensor 56 havinga light emitter and a light receiver which are spaced apart from eachother as shown in FIGS. 8, 10 and 11 when the plate portion 50 a passesbetween the light emitter and the light receiver of the photo sensor 56.The plate portion 50 a and the photo sensor 56 constitute a photointerrupter. The two photo sensors 55 and 56 are fixed in two fixingholes 15 a 1 and 15 a 2 (see FIG. 8) formed on a front wall of thehousing 11 to be supported thereby.

The present embodiment of the zoom lens camera has an image-shakedetection sensor 57 (see FIG. 5) which detects the angular velocityaround two axes (the vertical and horizontal axes of the camera)orthogonal to each other in a plane perpendicular to the photographingoptical axis Z1. The magnitude and the direction of camera shake(vibrations) are detected by the image-shake detection sensor 57. Thecontrol circuit 14 a determines a moving angle by time-integrating theangular velocity of the camera shake in the two axial directions,detected by the image-shake detection sensor 57. Subsequently, thecontrol circuit 14 a calculates from the moving angle the moving amountsof the image on a focal plane (imaging surface/light receiving surfaceof the CCD 13 g) in the x-axis direction and in the y-axis direction.The control circuit 14 further calculates the driving amounts and thedriving directions of the horizontal moving frame 32 and the verticalmoving frame 36 for the respective axial directions (driving pulses forthe first stepping motor 46 and the second stepping motor 53) in orderto counteract the camera shake. Thereupon, the first stepping motor 46and the second stepping motor 53 are actuated and the operations thereofare controlled in accordance with the calculated values. In this manner,each of the horizontal moving frame 32 and the vertical moving frame 36is driven in the calculated direction by the calculated amount in orderto counteract the shake of the photographing optical axis Z1 to therebystabilize the image on the focal plane. The camera can be put into thisimage stabilization mode by turning on a photographing mode selectswitch 14 e (see FIG. 5). If the switch 14 e is in an off-state, theimage stabilizing capability is deactivated so that a normalphotographing operation is performed.

The present embodiment of the zoom lens camera uses part of theabove-described image stabilizing mechanism to perform the retractingoperation (radially retracting operation) of the third lens group 13 e,the low-pass filter 13 f and the CCD 13 g toward the off-optical-axisretracted position Z2 into the retraction space SP when the zoom lens 10is retracted from a photographic state. As shown in FIGS. 22 and 23, aretracting lever (swing member) 60 is provided below the vertical movingframe 36. The retracting lever 60 is pivoted on a pivot shaft (rotationaxis of the swing member) 60 a to be rotatable (swingable) thereabout. Acoaxial gear (rotation transmitting device) 61 is installed adjacent tothe retracting lever 60, and is coaxially provided on the pivot shaft 60a to be rotatable on the pivot shaft 60 a. A rotational force istransferred from an interconnecting gear (rotation transmitting device)64 to the coaxial gear 61 via two relay gears (rotation transmittingdevice) 62 and 63. The pivot shaft 60 a, which serves as the rotationaxis of each of the retracting lever 60 and the coaxial gear 61, therotation axes of the relay gears 62 and 63, and the rotation axis of theinterconnecting gear 64 are each parallel to the rotation center axis Z0(and the photographing optical axis Z1).

As shown in FIGS. 9, 22 and 23, the retracting lever 60 is provided inthe vicinity of the pivot shaft 60 a with a rotation transfer protrusion60 b having a sector-shaped cross section and projecting forward in theoptical axis direction. The coaxial gear 61 is provided, at a rear endthereof, with a rotation transfer protrusion 61 a which projectsrearward in the optical axis direction, has the same diameter of that ofthe rotation transfer protrusion 60 b, and is coaxial with the pivotshaft 60 a. Namely, the rotation transfer protrusion 60 b and therotation transfer protrusion 61 a have the same diameter and arepositioned on the pivot shaft 60 a to be circumferentially engageablewith each other. The coaxial gear 61 transfers a rotation thereof to theretracting lever 60 by engaging the rotation transfer protrusion 61 awith the rotation transfer protrusion 60 b of the retracting lever 60.When the coaxial gear 61 rotates in a direction to disengage therotation transfer protrusion 61 a from the rotation transfer protrusion60 b, the rotational force of the coaxial gear 61 is not transferred tothe retracting lever 60. The retracting lever 60 is biased to rotatecounterclockwise as viewed in FIGS. 22 and 23 by a torsion spring(rotational biasing member) 60 c, and the housing 11 is provided thereinwith a stop projection 65 (see FIGS. 13, 14, 22 and 23) which definesthe limit of rotation of the retracting lever 60 in the biasingdirection of the torsion spring 60 c. Namely, the retracting lever 60comes in contact with the stop projection 65 as shown in FIG. 23 whenfully rotated counterclockwise as viewed in FIGS. 22 and 23.

The vertical moving frame 36 is provided on a bottom surface thereofwith an abutment surface 66 consisting of an arc-shaped surface 66 a anda leading surface 66 b. The arc-shaped surface 66 a has an arc shapewhich corresponds to an arc pivoted on the axis of the pivot shaft 60 aof the retracting lever 60, and the leading surface 66 b is formed as aflat inclined surface. The lowermost point of the leading surface 66 bis located at the portion thereof which is connected to the arc-shapedsurface 66 a, and the leading surface 66 b gradually rises in adirection away from the arc-shaped surface 66 a (in a direction toapproach the left side surface of the vertical moving frame 36 as viewedin FIGS. 22 and 23).

The interconnecting gear 64 is provided with a gear portion 64 a and arotation restricting portion 64 b at different positions in the axialdirection of interconnecting gear 64. The rotation restricting portion64 b has a non-circular (D-shaped) cross-sectional shape and includes alarge-diameter cylindrical portion 64 b 1 and a flat portion 64 b 2. Thelarge-diameter cylindrical portion 64 b 1 has an incomplete cylindricalshape having a diameter larger than that of the gear portion 64 a. Theflat portion 64 b 2 is formed on the rotation restricting portion 64 bin a manner so that a part of the large diameter cylindrical portion 64b 1 appears to be cut off to form a nearly flat shape. In an area inwhich the flat portion 64 b 2 is formed, the tips of the teeth of thegear portion 64 a project radially outwards from the rotationrestricting portion 64 b. The flat portion 64 b 2 is formed as a flatsurface which includes a straight line parallel to the axis of rotationof the interconnecting gear 64.

The interconnecting gear 64 is positioned to face the outer surface ofthe helicoid ring 18. The spur gear 18 c faces either the gear portion64 a of the interconnecting gear 64 (in the state shown in FIGS. 11 and14) or the rotation restricting portion 64 b (in the state shown FIGS.10 and 13) depending on the axial position (and the type of motion) ofthe helicoid ring 18 in the optical axis direction. When the helicoidring 18 rotates at a fixed position as described above, the spur gear 18c is engaged with the gear portion 64 a. As the helicoid ring 18 movesin the retracting direction from the fixed-position rotating state, thespur gear 18 c is disengaged from the interconnecting gear 64 to facethe rotation restricting portion 64 b, so that the transfer of rotationof the helicoid ring 18 to the interconnecting gear 64 is stopped.

The operation of the retracting lever 60 will be discussed in detailhereinafter. FIG. 23 shows elements of the image stabilizing mechanismand the retracting mechanism in a state where the zoom lens 10 is set atthe wide-angle extremity. In this state, the third lens group 13 e, thelow-pass filter 13 f and the CCD 13 g are positioned on thephotographing optical axis Z1 (see the upper half of the zoom lens 10shown in FIG. 2), and also the helicoid ring 18 is in a state where thehelicoid ring 18 is only allowed to rotate at a fixed position in theoptical axis direction (see FIG. 6) while the gear portion 64 a of theinterconnecting gear 64 is engaged with the spur gear 18 c of thehelicoid ring 18. When the helicoid ring 18 rotates in the retractingdirection from the wide-angle extremity, the coaxial gear 61 rotatesclockwise as viewed in FIG. 23 via the interconnecting gear 64 and therelay gears 62 and 63. As shown in FIG. 23, since the rotation transferprotrusion 61 a and the rotation transfer protrusion 60 b are slightlyapart from each other when the zoom lens 10 is set at the wide-angleextremity, no rotational force is transferred from the coaxial gear 61to the retracting lever 60 for a short period of time after the coaxialgear 61 starts rotating. Accordingly, the retracting lever 60 is held inthe position shown in FIG. 23 where the retracting lever 60 is incontact with the stop projection 65 due to the biasing force of thetorsion spring 60 c. Thereafter, upon the rotation transfer protrusion61 a coming into contact with the rotation transfer protrusion 60 b andpressing the rotation transfer protrusion 60 b, the retracting lever 60starts rotating clockwise with respect to FIG. 23 against the biasingforce of the torsion spring 60 c. In the present embodiment, the timingof the commencement of rotation of the retracting lever 60 substantiallycorresponds to the angular position θ2 at which the cam ring 26 startsretracting in the optical axis direction from the fixed positionrotation state (see FIG. 6).

When the retracting lever 60 rotates clockwise from the angular positionshown in FIG. 23, a force-applying end (force applying portion) 60 dformed at the free end of the retracting lever 60 is brought intocontact with the leading surface 66 b of the abutment surface 66 of thevertical moving frame 36. A further clockwise rotation of the retractinglever 60 causes the retracting lever 60 to lift (push) the verticalmoving frame 36 according to the inclined shape of the leading surface66 b, thus causing the vertical moving frame 36 to move upward in thehousing 11 along the vertical guide shaft 38.

On and after the angular position exceeding θ1 shown in FIG. 6, when thehelicoid ring 18 rotates in the retracting direction, the rotatingoperation of the helicoid ring 18 at a fixed position in the opticalaxis direction ends, and subsequently the helicoid ring 18 starts movingrearward in the optical axis direction while rotating. Thereupon, thespur gear 18 c of the helicoid ring 18 is disengaged from the gearportion 64 a of the interconnecting gear 64, which in turn faces theflat portion 64 b 2 of the rotation restricting portion 64 b. Since eachof the spur gear 18 c and the gear portion 64 a has a predeterminedlength in the optical axis direction, the engagement between the spurgear 18 c and the gear portion 64 a is not released at once immediatelyafter the fixed-position rotating state of the helicoid ring 18 changesto the rotating and retracting state thereof at the angular position θ1,but is released at an angular position θ3 at which the helicoid ring 18further retracts in the retracting direction by a small amount ofmovement. Due to this disengagement of the spur gear 18 c from the gearportion 64 a, the rotational force of the helicoid ring 18 is no longertransferred to the interconnecting gear 64, so that the upwardrotational motion of the retracting lever 60 is terminated. FIGS. 15 and22 show the retracting lever 60 in a state in which the upwardrotational motion thereof has been terminated. As can be seen in FIG.22, the force-applying end 60 d of the retracting lever 60 is in contactwith the arc-shaped surface 66 a after passing the boundary between thearc-shaped surface 66 a and the leading surface 66 b. In this state, thevertical moving frame 36 lifted by the retracting lever 60 have beenmoved into the retraction space SP in the housing 11 as shown in FIG. 1.

The retracting operation of the zoom lens 10 is not completed at theangular position θ3 where the upward retracting motion of the verticalmoving frame 36 is completed; the helicoid ring 18 and the cam ring 26further move rearward in the optical axis direction while rotating.Thereafter, when the helicoid ring 18 and the cam ring 26 reach theirrespective retracted positions shown in FIG. 1, the cylindrical portion25 b of the second lens group support frame 25 that holds the secondlens group 13 d is retracted into the space in the housing 11 which isformerly occupied by the vertical moving frame 36 when the zoom lens 10is in a photographic state. In this manner, the thickness of thephotographing optical system in the optical axis direction can bereduced in the retracted state of the zoom lens 10, which makes itpossible to reduce the thickness of the zoom lens 10, which in turnmakes it possible to reduce the thickness of a camera incorporating thezoom lens 10.

In the above-described retracting operation of the zoom lens 10, afterthe zoom lens 10 retracts to the angular position θ3 where theengagement between the gear portion 64 a of the interconnecting gear 64and the spur gear 18 c of the helicoid ring 18 is released, the spurgear 18 c faces the flat portion 64 b 2 of the rotation restrictingportion 64 b. In this state where the spur gear 18 c faces the flatportion 64 b 2, the flat portion 64 b 2 is positioned in close vicinityof the tooth top (outermost periphery/addendum circle) of the spur gear18 c. Therefore, even if the interconnecting gear 64 tries to rotate,the flat portion 64 b 2 abuts against the outer periphery of the spurgear 18 c to prevent the interconnecting gear 64 from rotating (seeFIGS. 10 and 13). In this manner, the interconnecting gear 64 isprevented from rotating accidentally in the retracted state of the zoomlens 10, and thus the retracting lever 60 can be securely locked in theupper rotational position. In other words, in the retracted state shownin FIG. 22, although the retracting lever 60 is biased counterclockwiseas viewed in FIG. 22 by the torsion spring 60 c, the retracting lever 60is prevented from rotating counterclockwise by a gear train consistingof the coaxial gear 61, the pair of relay gears 62 and 63 and theinterconnecting gear 64. The abutting physical relationship between theflat portion 64 b 2 of the interconnecting gear 64 and the spur gear 18c serves as a rotation restricting device for restricting rotation ofthe retracting lever 60. Therefore, the retracting lever 60 can besecurely held in a halting state without any complicated lockingmechanism.

In a state in which the vertical moving frame 36 is radially retractedupward completely out of the linear retracting path of the first andsecond lens groups 13 a and 13 d, the force-applying end 60 d of theretracting lever 60 abuts against the arc-shaped surface 66 a which hasan arc-shaped surface having its center on the axis of the pivot shaft60 a of the retracting lever 60. Therefore, even if the angle of theretracting lever 60 is changed, the vertical position of the verticalmoving frame 36 is not changed and held constant so long as theforce-applying end 60 d abuts against the arc-shaped surface 66 a.

The operation of the retracting mechanism from the wide-angle extremityto the retracted position has been described above. On the other hand,in the zooming range from the wide-angle extremity to the telephotoextremity, the spur gear 18 c of the helicoid ring 18 rotating at afixed position remains engaged with the gear portion 64 a of theinterconnecting gear 64, and thus the interconnecting gear 64 is rotatedaccording to the rotation of the helicoid ring 18. However, rotating thehelicoid ring 18 from the wide-angle extremity state shown in FIG. 23toward the telephoto extremity causes the coaxial gear 61 to rotatecounterclockwise as viewed in FIG. 23, i.e., in a direction to move therotation transfer protrusion 61 a away from the rotation transferprotrusion 60 b. Therefore, in the zooming range from the wide-angleextremity to the telephoto extremity, no rotational force is transferredto the retracting lever 60, and the retracting lever 60 is held at theangular position shown in FIG. 23. In this manner, the range of rotationof the retracting lever 60 can be minimized, thereby preventing anincrease in size of the zoom lens barrel.

When the vertical moving frame 36 is retracted upward to theoff-optical-axis retracted position Z2 as shown in FIG. 24, the positionrestricting surface 32 e that is provided on the arm portion 32 b of thehorizontal moving frame 32 is disengaged from the operation pin 40 bthat is provided on the horizontal driving lever 40. This disengagementof the position restricting surface 32 e from the operation pin 40 bcauses the horizontal moving frame 32 to move leftward as viewed in FIG.24 by the biasing force of the horizontal moving frame biasing spring 37up to a point at which the frame portion 32 a of the horizontal movingframe 32 abuts against the motion restricting frame 36 a of the verticalmoving frame 36. From this state, upon the vertical moving frame 36being moved down to the photographing optical axis Z1, the inclinedsurface 32 d of the horizontal moving frame 32 comes in contact with theoperation pin 40 b as shown by two-dot chain lines in FIG. 24. Theinclined surface 32 d is inclined so as to guide the operation pin 40 bto the position restricting surface 32 e side according to the downwardmotion of the vertical moving frame 36. Therefore, upon the verticalmoving frame 36 being moved down to the photographing position, theoperation pin 40 b is again engaged with the position restrictingsurface 32 e as shown in FIG. 20 and the frame portion 32 a of thehorizontal moving frame 32 returns to the neutral position thereofbetween the motion restricting frame 36 a and the motion restrictingframe 36 b.

As described above, during the retracting operation of the zoom lens(lens barrel) 10, the rotational motion of the retracting lever 60causes the vertical moving frame 36 to be lifted from the position onthe photographing optical axis Z1 to the radially-retracted position.Thus, the third lens group 13 e, the low-pass filter 13 f, and the CCD13 g are radially retracted so as to be positioned at theoff-optical-axis retracted position Z2.

As shown in FIGS. 14 and 23, the radially-retractable optical elementsincluding the third lens group 13 e, the low-pass filter 13 f, and theCCD 13 g are located in the photographing position on the photographingoptical axis Z1. In this state, as can be seen by comparing FIGS. 13 and14, or FIGS. 22 and 23, the force applying end 60 d of the retractinglever 60 is located farthest, in the horizontal direction (x-axisdirection) of the camera, from the vertical guide shaft 38 which guidesthe vertical moving frame 36. Namely, the vertical moving frame 36 andthe vertical guide shaft 38 constitute a linear guiding device forguiding the radially-retractable optical elements. The force applyingend 60 d gradually approaches the vertical guide shaft 38 in thehorizontal direction of the camera, as the vertical moving frame 36 ismoved upward toward the off-optical-axis retracted position Z2. Thepivot shaft 60 a of the retracting lever 60 is provided near thevertical guide shaft 38, and the extending direction of the verticalguide shaft 38 is orthogonal (i.e., y-axis direction) to the horizontaldirection of the camera. Therefore, as the vertical moving frame 36moves upward toward the off-optical-axis retracted position Z2, thehorizontal distance between the force applying end 60 d and the pivotshaft 60 a gradually decreases. In this manner, the vertical movingamount of the vertical moving frame 36 per unit of rotation angle of theretracting lever 60 (a predetermined rotation angle) becomes larger asthe vertical moving frame 36 approaches the photographing optical axisZ1. Conversely, the vertical moving amount of the frame 36 per unit ofrotation angle of the retracting lever 60 becomes gradually smaller asthe vertical moving frame 36 approaches the off-optical-axis retractedposition Z2. By setting the pivotal position of the retracting lever 60as above, the variation of the load on the driving system can be reducedwhen the third lens group 13 e, the low-pass filter 13 f, and the CCD 13g are driven for retraction to the off-optical-axis retracted positionZ2.

More specifically, the vertical moving frame biasing spring 39 is formedof an extension spring and is gradually extended as the vertical movingframe 36 moves upward for retraction from the photographing position(the photographing optical axis Z1) to the radially-retracted position(the off-optical-axis retracted position Z2). Therefore, the biasingforce of the spring 39 gradually increases with the motion of thevertical moving frame 36 and becomes maximum when the vertical movingframe 36 reaches the radially-retracted position. Conversely, the movingamount of the vertical moving frame 36 per unit of rotation angle of theretracting lever 60 decreases in nearly inverse proportion to theincrease of the biasing force of the spring 39. Therefore, even when thebiasing force of the spring 39 gradually increases, the moving amount ofthe vertical moving frame 36 per unit of time gradually decreases. As aresult, the load on the driving mechanism of the retracting lever 60 perunit of time does not change as much as the variation amount of thebiasing force of the spring 39. The lever ratio of the retracting lever60, the position of the pivot shaft 60 a are set so that the loadvariation per unit of time is reduced (i.e., load extremes per unit oftime are reduced) as much as possible. Therefore, the variation of theresistance for action when the retracting lever 60 is driven can bereduced, and the output power of the driving source for driving thelever 60 can be reduced.

Specifically, the rotational driving force of the retracting lever 60 isobtained from the rotation of the helicoid ring 18, and the helicoidring 18 is driven by the zoom motor MZ. If the variation of theresistance for the action of the retracting lever 60 is large, a motormust be provided which has an output power adaptable to the maximumresistance value. However, since the variation of the resistance for theaction of the retracting lever 60 is suppressed to a minimum in thepresent invention, the load variation on the zoom motor MZ is reducedwhen the vertical moving frame 36 is driven for retraction. Accordingly,a small lightweight motor with a low maximum power can be employed asthe zoom motor MZ, resulting in an advantage in reducing the size of thezoom lens barrel 10 and the power consumption.

Although the present invention has been described based on the aboveillustrated embodiment, the present invention is not limited solelythereto. For example, although the number of components is reduced byemploying the zoom motor MZ also serving as the driving source of theretracting lever 60 in the illustrated embodiment, if a driving sourceis provided independently for driving the lever 60, a similar effect canbe obtained for this driving source.

Furthermore, although the above embodiment is applied to a zoom lensbarrel, the present invention can be applied to a lens barrel other thana zoom lens, so long as the lens barrel is of a type which is operatedat least in a photographing state and a non-photographing (retracted)state.

Obvious changes may be made in the specific embodiments of the presentinvention described herein, such modifications being within the spiritand scope of the invention claimed. It is indicated that all mattercontained herein is illustrative and does not limit the scope of thepresent invention.

1. A lens barrel comprising: a radially-retractable optical elementconstituting a part of photographing optical system, saidradially-retractable optical element being movable between aphotographing position located on an optical axis of said photographingoptical system, and a radially-retracted position located on anoff-optical-axis position; a biasing device for biasing saidradially-retractable optical element toward said photographing position;and a swing member which is rotatable about a rotation axis extendingparallel to said optical axis, said swing member being rotated so as topush said radially-retractable optical element against a biasing forceof said biasing device to move said radially-retractable optical elementto said radially-retracted position; wherein said radially-retractableoptical element and said swing member are mutually positioned so that amoving amount of said radially-retractable optical element per unit ofrotation angle of said swing member gradually decreases as saidradially-retractable optical element moves from said photographingposition to said radially-retracted position.
 2. The lens barrelaccording to claim 1, wherein the biasing force of said biasing devicevaries according to the movement of said radially-retractable opticalelement and becomes maximum when said radially-retractable opticalelement is positioned at said radially-retracted position.
 3. The lensbarrel according to claim 1, further comprising a linear guiding device,wherein said radially-retractable optical element is linearly guided bysaid linear guiding device so as to move between said photographingposition and said radially-retracted position in a direction orthogonalto said optical axis.
 4. The lens barrel according to claim 3, whereinsaid linearly guiding device of said radially-retractable opticalelement comprises: a guide shaft extending parallel to a retractingdirection of said radially-retractable optical element; and anoptical-element holder which holds said radially-retractable opticalelement, said optical-element holder slidably supported by said guideshaft so as to move between said photographing position and saidradially-retracted position of said radially-retractable opticalelement; wherein said swing member rotationally moves while pushing saidoptical-element holder against the biasing force of said biasing devicewhen said radially-retractable optical element is moved from saidphotographing position to said radially-retracted position.
 5. The lensbarrel according to claim 4, wherein said rotation axis of said swingmember is positioned so that a force applying portion, at which saidswing member pushes said optical-element holder, gradually approachessaid guiding shaft as said radially-retractable optical element movesfrom said photographing position to said radially-retracted position. 6.The lens barrel according to claim 5, wherein said swing membercomprises a rotatable lever, one end thereof being rotatably supportedat said rotation axis, and the other end thereof being provided withsaid force applying portion.
 7. The lens barrel according to claim 1,further comprising a rotational biasing member for rotationally biasingsaid swing member in a direction so as to hold said radially-retractableoptical element in said photographing position.
 8. The lens barrelaccording to claim 1, further comprising: a rotational ring which isdriven to rotate about a rotational axis parallel to said optical axisby a motor so as to cause at least one optical element, which isdifferent from said radially-retractable optical element, to move alongthe optical axis; and a rotation transmitting device for transmitting arotational driving force of said rotational ring to said swing memberwhen said radially-retractable optical element moves from saidphotographing position to said radially-retracted position.
 9. The lensbarrel according to claim 1, wherein said radially-retractable opticalelement comprises an image sensor provided in an imaging position ofsaid photographing optical system.
 10. The lens barrel according toclaim 1, further comprising an image-stabilizer which detects vibrationapplied to said photographing optical system and moves saidradially-retractable optical element in a plane orthogonal to saidoptical axis, when said radially-retractable optical element is in saidphotographing position, to counteract image shake in accordance with adirection and a magnitude of said vibration.
 11. A lens barrelcomprising: a radially-retractable optical element constituting a partof a photographing optical system, said radially-retractable opticalelement being movable between a photographing position located on anoptical axis of said photographing optical system, and aradially-retracted position located on an off-optical-axis position; abiasing device for biasing said radially-retractable optical elementtoward said photographing position; and a swing member which isrotatable about a rotation axis extending parallel to said optical axis,said swing member being rotated so as to push said radially-retractableoptical element against a biasing force of said biasing device to movesaid radially-retractable optical element to said radially-retractedposition; wherein a biasing force of said biasing device graduallyincreases, and a moving amount of said radially-retractable opticalelement per unit rotation angle of said swing member graduallydecreases, as said radially-retractable optical element moves from saidphotographing position to said radially-retracted position.